KDE

KDE is a software project currently comprising of a desktop environment known as Plasma, a collection of libraries and frameworks (KDE Frameworks) and several applications (KDE Applications) as well. KDE upstream has a well maintained UserBase wiki. Detailed information about most KDE applications can be found there.

KDE applications and language packs

To install the full set of KDE Applications, install the kde-applications group or the kde-applications-meta meta-package. Note that this will only install applications, it will not install any version of Plasma.

Most KDE packages ship their own translations. The exception is KDE4-based packages from kde-applications. If you need language files for these packages, install kde-l10n-yourlanguagehere (e.g. kde-l10n-de for the German language). For a full list of available languages see the kde-l10n split package.

Unstable releases

Starting Plasma

Note: Although it is possible to launch Plasma under Wayland, there are some missing features and known problems as of Plasma 5.11. See the Plasma 5.11 Errata for a list of issues and the Plasma on Wayland workboard for the current state of development. Use Xorg for the most complete and stable experience.

From the console

To start Plasma with xinit/startx, append exec startkde to your .xinitrc file. If you want to start Xorg at login, please see Start X at login. To start a Plasma on Wayland session from a console, run startplasmacompositor.

Configuration

Most settings for KDE applications are stored in ~/.config, but some older applications may use ~/.kde4. However, configuring KDE is primarily done through the System Settings application. It can be started from a terminal by executing systemsettings5.

Some Frameworks 5 applications can use KDElibs 4 configuration, after moving the configuration files to the new location. Examples are:

Konsole profiles from ~/.kde4/share/apps/konsole to ~/.local/share/konsole/

Application appearance from ~/.kde4/share/config/kdeglobals to ~/.config/kdeglobals

Personalization

Plasma desktop

Themes

Plasma themes define the look of panels and plasmoids. For easy system-wide installation, some themes are available in both the official repositories and the AUR.

The easiest way to install themes is by going through the System Settings > Workspace Theme > Desktop Theme > Get new Themes.

This will present a frontend for the KDE-Store that allows you to install, uninstall, or update third-party plasmoid scripts.

Splash and Lock screens are currently unavailable. To customize these screens, you have to modify the original theme found in /usr/share/plasma/look-and-feel/.
See this thread on the Kubuntu forums.

Qt and GTK+ Applications Appearance

For Qt4 applications to have a consistent appearance, there are two options:

Install breeze-kde4 and then pick Breeze as GUI Style in qtconfig-qt4; or install breeze-gtk and pick GTK+ as GUI Style.

GTK+

The recommended theme for a pleasant appearance in GTK+ applications is breeze-gtk or gnome-breeze-gitAUR, a GTK+ theme designed to mimic the appearance of Plasma's Breeze theme.
Install kde-gtk-config and select the installed GTK-theme for GTK2/GTK3-Theme in System Settings > Application Style > GNOME Application Style.

In some themes, tooltips in GTK+ applications have white text on white backgrounds making it difficult to read. To change the colors in GTK2 applications, find the section for tooltips in the .gtkrc-2.0 file and change it. For GTK3 application two files need to be changed, gtk.css and settings.ini.
It might also help to uncheck the option to Apply colors to non-Qt applications under System Settings > Colors.

Some GTK2 programs like vuescan-binAUR still look hardly usable due to invisible checkboxes with the Breeze or Adwaita skin in a Plasma session. To workaround this, install and select e.g. the Numix-Frost-Light skin of the numix-frost-themesAUR under System Settings > Application Style > GNOME Application Style (GTK) > Select a GTK2 Theme:. Numix-Frost-Light looks similar to Breeze.

Widgets

Plasmoids are little scripted (plasmoid scripts) or coded (plasmoid binaries) KDE applications designed to enhance the functionality of your desktop.

The easiest way to install plasmoid scripts is by right-clicking onto a panel or the desktop and choosing Add Widgets > Get new Widgets > Download Widgets.
This will present a nice frontend for https://store.kde.org/ that allows you to install, uninstall, or update third-party plasmoid scripts with literally just one click.

Window decorations

There you can also directly download and install more themes with one click, and some are available in the AUR.

Icon themes

Icon themes can be installed and changed on System Settings > Icons.

Note: Although all modern Linux desktops share the same icon theme format, desktops like GNOME use fewer icons (esp. in menus and toolbars). Themes developed for such desktops usually lack icons required by Plasma and KDE apps. It is recommended to install Plasma compatible icon themes instead.

Fonts

Fonts in a Plasma session look poor

After the installation, be sure to log out and back in. You should not have to modify anything in System Settings > Fonts. If you are using qt5ct, the settings in Qt5 Configuration Tool may override the font settings in System Settings.

If you have personally set up how your Fonts render, be aware that System Settings may alter their appearance. When you go System Settings > Fonts System Settings will likely alter your font configuration file (fonts.conf).

There is no way to prevent this, but, if you set the values to match your fonts.conf file, the expected font rendering will return (it will require you to restart your application or in a few cases restart your desktop). Note that Gnome's Font Preferences also does this.

Fonts are huge or seem disproportional

Space efficiency

The Plasma Netbook shell has been dropped from Plasma 5, see the following KDE forum post
However, you can achieve something similar by editing the file ~/.config/kwinrc adding
BorderlessMaximizedWindows=true in the [Windows] section.

Samba/Windows support

If you want to have access to Windows services, install Samba (package samba).

The Dolphin share functionality requires the package kdenetwork-filesharing and usershares, which the stock smb.conf does not have enabled. Instructions to add them are in Samba#Creating usershare path, after which sharing in Dolphin should work out of the box after restarting Samba.

Plasma's abilities to access SMB shares are limited, though. Writing to Windows shares is problematic and opening files from such shares, e.g. large videos, makes Plasma copying the whole file to the local system first.
To workaround this, you can install a GTK based file browser like thunar with gvfs and gvfs-smb (and gnome-keyring for saving login credentials) to access SMB shares in a more able way.
Another possible workaround is to mount a Samba share via cifs-utils to make it look to Plasma like if the SMB share was just a normal local folder and thus can be accessed normally.
The mount command could look like the following for write access to a public share:

It migh or it might not be necessary to append .local to the hostname. For some NAS devices it might also be necessary to append vers=1.0 to the argument line to enforce SMB 1.0 compatibility.

An easier solution is to use samba-mounter-gitAUR, which offers basically the same functionality via an easy to use option located at System Settings > Network Drivers.

KDE Desktop activities

KDE Desktop Activities are special workspaces where you can select specific settings for each activity that apply only when you are using said activity.

Power saving

Installpowerdevil for an integrated power saving service called "Powerdevil Power Management", that may adjust the power saving profile of the system and/or the brightness of the screen (if supported).

The factual accuracy of this article or section is disputed.

Reason: Regarding the note below, it might be that the problem is the logind setting LidSwitchIgnoreInhibited which defaults to yes. [3] (Discuss in Talk:KDE#)

Autostarting applications

Plasma can autostart applications and run scripts on startup and shutdown. To autostart an application, navigate to System Settings > Startup and Shutdown > Autostart and add the program or shell script of your choice. For applications, a .desktop file will be created, for shell scripts, a symlink will be created.

Note:

Programs can be autostarted on login only, whilst shell scripts can also be run on shutdown or even before Plasma itself starts.

Upstream prefers VLC but prominent Linux distributions (Kubuntu and Fedora-KDE for example) prefer GStreamer because that allows them to easily leave out patented MPEG codecs from the default installation. Both backends have a slightly different features set.

In the past other backends were developed as well but are no longer maintained and their AUR packages have been deleted.

Note:

Multiple backends can be installed at once and prioritized at System Settings > Multimedia > Backend.

If you choose the vlc backend, you may experience crashes every time kde wants to send you a audible warning (and in quite a number of other cases as well, see [4])

A possible fix is to run

# /usr/lib/vlc/vlc-cache-gen -f /usr/lib/vlc/plugins

Applications

The KDE project provides a suite of applications that integrate with the Plasma desktop. See the kde-applications group for a full listing of the available applications. Also see Category:KDE for related KDE application pages.

Aside from the programs provided in KDE Applications, there are many other applications available that can complement the Plasma desktop. Some of these are discussed below.

System administration

Terminate Xorg server through KDE System Settings

Navigate to the submenu System Settings > Input Devices > Keyboard > Advanced (tab) > "Key Sequence to kill the X server" and ensure that the checkbox is ticked.

KCM

KCM stands for KConfig Module. KCMs can help you configure your system by providing interfaces in System Settings, or through the command line with kcmshell5.

Desktop search

KDE implements desktop search with a software called Baloo, a file indexing and searching solution.

Baloo

Using and configuring Baloo

In order to search using Baloo on the Plasma desktop, start krunner (default keyboard shortcut ALT+F2) and type in your query. Within Dolphin press CTRL+F.

By default the Desktop Search KCM exposes only two options: A panel to blacklist folders and a way to disable it with one click.

Alternatively you can edit your ~/.config/baloofilerc file (info). Additionally the balooctl process can also be used. In order to disable Baloo run balooctl stop and balooctl disable.

Once you added additional folders to the blacklist or disabled Baloo entirely, a process named baloo_file_cleaner removes all unneeded index files automatically. They are stored under ~/.local/share/baloo/.

How do I index a removable device?

By default every removable device is blacklisted. You just have to remove your device from the blacklist in the KCM panel.

Web browsers

Konqueror — Part of the KDE project, supports two rendering engines – KHTML and the Chromium-based Qt WebEngine.

PIM

KDE offers its own stack for personal information management. This includes emails, contacts, calendar, etc. To install all the PIM packages, you could use the meta-package kde-meta-kdepim.

Akonadi

Akonadi is a system meant to act as a local cache for PIM data, regardless of its origin, which can be then used by other applications. This includes the user's emails, contacts, calendars, events, journals, alarms, notes, and so on.

Akonadi does not store any data by itself: the storage format depends on the nature of the data (for example, contacts may be stored in vCard format).

SQLite

KDE Telepathy

KDE Telepathy is a project with the goal to closely integrate Instant Messaging with the KDE desktop. It utilizes the Telepathy framework as a backend and is intended to replace Kopete.

To install all Telepathy protocols, install the telepathy group.
To use the KDE Telepathy client, install the telepathy-kde-meta package that includes all the packages contained in the telepathy-kde group.

The configuration through the GUI may be tricky: if the phone number is not accepted when configuring a new account in the KDE Telepathy client (with an error message complaining about an invalid parameter which prevents the account creation), insert it between single quotes and then remove the quotes manually from the configuration file (~/.local/share/telepathy/mission-control/accounts.cfg) after the account creation (if the quotes are not removed after, an authentication error should rise).

Note: The configuration file should be edited manually when KDE Telepathy is not running, e.g. when there is no KDE desktop session active, otherwise manual changes may be overwritten by the software.

Multimedia remote control: Use your phone as a remote for Linux media players.

WiFi connection: no usb wire or bluetooth needed.

RSA Encryption: your information is safe.

You will need to install KDE Connect both on your computer and on your Android. For PC side, install kdeconnect package. For Android side, install KDE Connect from Google Play or from F-Droid.

It is possible to use KDE Connect even if you do not use the Plasma desktop. For desktop environments that use AppIndicators, such as Unity, install indicator-kdeconnectAUR package as well.

Tips and tricks

Using an alternative window manager

The component chooser settings in Plasma does not allow changing the window manager anymore. [5]
In order to change the window manager used you need to set the KDEWMenvironment variable before KDE startup. [6] To do that you can create a script called set_window_manager.sh in ~/.config/plasma-workspace/env and export the KDEWM variable there. For example to use the i3 window manager :

~/.config/plasma-workspace/env/set_window_manager.sh

export KDEWM=/usr/bin/i3

And then make it executable :

$ chmod +x ~/.config/plasma-workspace/env/set_window_manager.sh

KDE/Openbox session

The openbox package provides a session for using KDE with Openbox. To make use of this session, select KDE/Openbox from the display manager menu.

For those starting the session manually, add the following line to your .xinitrc file:

exec openbox-kde-session

Re-enabling compositing effects

When replacing Kwin with a window manager which does not provide a Compositor (such as Openbox), any desktop compositing effects e.g. transparency will be lost. In this case, install and run a separate Composite manager to provide the effects such as Xcompmgr or Compton.

Disable opening application launcher with Super key (Windows key)

Troubleshooting

Configuration related

Many problems in KDE are related to configuration.

Plasma desktop behaves strangely

Plasma problems are usually caused by unstable Plasma widgets (colloquially called plasmoids) or Plasma themes. First, find which was the last widget or theme you had installed and disable it or uninstall it.

So, if your desktop suddenly exhibits "locking up", this is likely caused by a faulty installed widget. If you cannot remember which widget you installed before the problem began (sometimes it can be an irregular problem), try to track it down by removing each widget until the problem ceases. Then you can uninstall the widget, and file a bug report (https://bugs.kde.org/) only if it is an official widget. If it is not, it is recommended you find the entry on https://store.kde.org/ and inform the developer of that widget about the problem (detailing steps to reproduce, etc).

If you cannot find the problem, but you do not want all the settings to be lost, navigate to ~/.config:

$ for j in plasma*; do mv -- "$j" "${j%}.bak"; done

This command will rename all Plasma related configs to *.bak (e.g. plasmarc.bak) of your user and when you will relogin into Plasma, you will have the default settings back. To undo that action, remove the .bak file extension. If you already have *.bak files, rename, move, or delete them first. It is highly recommended that you create regular backups anyway. See Synchronization and backup programs for a list of possible solutions.

Clean cache to resolve upgrade problems

The problem may be caused by old cache. Sometimes after an upgrade, the old cache might introduce strange, hard to debug behaviour such as unkillable shells, hangs when changing various settings and several other problems such as ark being unable to unrar or unzip or amarok not recognizing any of your music. This solution can also resolve problems with KDE and Qt programmes looking bad following upgrade.

Rebuild your cache with the following commands:

$ rm ~/.config/Trolltech.conf
$ kbuildsycoca5 --noincremental

Clean akonadi configuration to fix KMail

First, make sure that KMail is not running. Then backup configuration:

Start SystemSettings > Personal and remove all the resources. Go back to Dolphin and remove the original ~/.local/share/akonadi and
~/.config/akonadi - the copies you made ensure that you can back-track if necessary.

Now go back to the System Settings page and carefully add the necessary resources. You should see the resource reading in your mail folders. Then start Kontact/KMail to see if it work properly.

Fix empty IMAP inbox

For some IMAP accounts, kmail will show the inbox as a container with all other folders of this account inside. Kmail does not show messages in the inbox container but in all other subfolders, see KDE Bug 284172. To solve this problem simply disable the server side subscribition in the kmail account settings.

Getting current state of KWin for support and debug purposes

This command prints out a wonderful summary of the current state of KWin including used options, used compositing backend and relevant OpenGL driver capabilities. See more on Martin's blog.

KF5/Qt5 applications do not display icons in i3/fvwm/awesome

Graphical related problems

Plasma keeps crashing with legacy Nvidia

This is caused by a bug in Plasma when using the Nvidia-304xx driver. Rather than disabling compositing, create a file kwin.sh in ~/.config/plasma-workspace/env/ with the following contents:

#!/bin/sh
export KWIN_EXPLICIT_SYNC=0

Then go to System Settings > Startup and Shutdown > Autostart and Check/Add the script as a pre-KDE startup file.

Applications do not refresh properly

If you use 3D-accelerated composition with Intel, you might find that the Plasma panel and other applications do not refresh properly (stay frozen). Some Intel drivers have problems with EGL. Go to System Settings > Display and Monitor > Compositor. Set OpenGL interface to OpenGL 3.1. If that does not work, see Intel graphics#SNA issues for alternative solutions.

Plasma has desktop effects enabled by default and e.g. not every game will disable them automatically. You can disable desktop effects in System Settings > Desktop Effects and you can toggle desktop effects with Alt+Shift+F12. Additionally, you can create custom KWin rules to automatically disable/enable compositing when a certain application/window starts under System Settings > Window Management > Window Rules.

Flickering in fullscreen when compositing is enabled

Screen tearing with Nvidia

By default, KWin compositing suffers from tearing when used with the proprietary Nvidia driver. To work around this, create a file kwin.sh in ~/.config/plasma-workspace/env/ with the following contents:

#!/bin/sh
export __GL_YIELD="USLEEP"

This however does only work with OpenGL compositing.

Plasma cursor sometimes shown incorrecty

Create the directory ~/.icons/default and inside a file named index.theme with the following contents:

ALSA related problems

"Falling back to default" messages when trying to listen to any sound

The audio playback device name_of_the_sound_device does not work.
Falling back to default

Go to System Settings > Multimedia > Phonon and set the device named default above all the other devices in each box you see.

MP3 files cannot be played when using the GStreamer Phonon backend

This can be solved by installing the GStreamer libav plugin (package gst-libav). If you still encounter problems, you can try changing the Phonon backend used by installing another such as phonon-qt4-vlc or phonon-qt5-vlc.
Then, make sure the backend is preferred via System Settings > Multimedia > Backend.

It is not recommended to turn off the KWallet password saving system in the user settings as it is required to save encrypted credentials like WiFi passphrases for each user. Persistently occuring KWallet dialogs can be the consequence of turning it off.
In case you find the dialogs to unlock the wallet annoying when applications want to access it, you can let the login managers SDDM and LightDM unlock the wallet at login automatically, see KDE Wallet. The first wallet needs to be generated by KWallet (and not user-generated) in order to be usable for system program credentials.
In case you want the wallet credentials not to be opened in memory for every application, you can restrict applications from accessing it with kwalletmanager in the KWallet settings.
If you do not care for credential encryption at all, you can simply leave the password forms blank when KWallet asks for the password while creating a wallet. In this case, applications can access passwords without having to unlock the wallet first.